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acceptable frequency response for a room?
Old 3rd July 2007
  #1
Gear Addict
 
mahler007's Avatar
 

acceptable frequency response for a room?

Hi Slutz,
I would like to test the frequency response of my room, and am just curious what a general, acceptable ball park figure is for its behavior... Naturally, I realize that as flat as possible is best, but somewhat impossible, especially given my circumstances.

This being said, what range of DB is acceptable between the highest and lowest frequencies? Is a range of 10 db or so considered acceptable, or is that pretty bad?

I am using a pink noise generator, an Earthworks QTC 40 onmi directional mic, and analyzing with the Wavesd PAZ frequency analyzer. Any advice or tips would be *greatly* appreciated.

Many thanks,
Andrew
Old 3rd July 2007
  #2
Lives for gear
 

+ - 10 db should be ok.

Room treatment isn`t all about frequency response.... There are a few more things that you should take care.
Old 3rd July 2007
  #3


Frequency response is the least of your worries.

The deep nulls are a problem.

Most of the other issues have to do with transient behavior - like early reflections, flutter, focusing, and ringing.

Also, control rooms and recording spaces are different in terms of what you want.




-tINY

Old 3rd July 2007
  #4
Gear Guru
 
Glenn Kuras's Avatar
Quote:
Originally Posted by nandoanalog View Post
+ - 10 db should be ok.

Room treatment isn`t all about frequency response.... There are a few more things that you should take care.
Agreed on the + - 10 db. And yes ringing is a huge problem.
Old 3rd July 2007
  #5
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norman_nomad's Avatar
Quote:
Originally Posted by mahler007 View Post
Hi Slutz,
I would like to test the frequency response of my room, and am just curious what a general, acceptable ball park figure is for its behavior... Naturally, I realize that as flat as possible is best, but somewhat impossible, especially given my circumstances.

This being said, what range of DB is acceptable between the highest and lowest frequencies? Is a range of 10 db or so considered acceptable, or is that pretty bad?

I am using a pink noise generator, an Earthworks QTC 40 onmi directional mic, and analyzing with the Wavesd PAZ frequency analyzer. Any advice or tips would be *greatly* appreciated.

Many thanks,
Andrew
+ - 10db is actually pretty good (remember that means only a 10 db difference between the loudest and quietest sounds produced in the room as measured from 20hz to 20k) .... room size and dimensions will really determine how easy it is to get there.

There may be a lot of people who say their room is + - 10db or better but often their testing methods are dubious. A lot of small bedroom "studios" are easily + - 30db if there is little or no treatment in the room. Dropping these figures down to + - 10db is tough!

I've read that even professional control room designers are happy if they can get a room within + - 6db.

I wouldn't use pink noise personally but a progressive sine sweep that steps 1hz at a time through the entire frequency spectrum. Likely you'll see most variation below 500hz.

So there you go.
Old 3rd July 2007
  #6
Gear Addict
 
mahler007's Avatar
 

hey,
Thanks so much for the replies, y'all.

I will do the 1 Hz sine tone tests as well, but can you tell me, or point me to a resource that tells me, how I can test for ringing, deep nulls, and all the other gremlins?

I should probably say that my room is already treated with broadband bass absorbers in 2 corners and high frequency absorbers on the front wall, ceiling above the mix position, and at the ceiling/wall joints. The room is a bit unusual as the right side opens out into a much larger rectangular room, hence the reason for using the bass absorbers in only two corners (the other two corners are non existent as a result of the opening into the larger room)

I am primarily using my space for mixing, editing, and "mastering."

Thanks again!

Cheers,
Andrew
Old 4th July 2007
  #7
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mahler007's Avatar
 

bump?
Old 4th July 2007
  #8
Gear Guru
 
Ethan Winer's Avatar
 

Andrew,

Quote:
I will do the 1 Hz sine tone tests as well, but can you tell me, or point me to a resource that tells me, how I can test for ringing, deep nulls, and all the other gremlins?
This article explains how I use the ETF software:

RealTraps - Optimizing Acoustic Treatment using ETF

ETF and its sister program R+D are for Windows. There's also FuzzMeasure for Macs, and the freeware Room EQ Wizard. Google will find them for you.

Also, to answer your original question, most untreated rooms have numerous peaks and deep nulls that span more than 30 dB below 300 Hz. If you can get the response to within a 10 dB window at bass frequencies you're doing really well.

--Ethan
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